Adjustable height practice golf tee

ABSTRACT

This invention concerns an adjustable height practice golf tee for use with any of the existing golf hitting mats used at or incorporated into golf driving ranges, public and private indoor hitting areas, golf club fitting, testing and swing teaching stations, electronic golf swing analyzers and golf simulation video games. The invention incorporates a hidden thread design into two-piece and three-piece models to provide a greater range of adjustment and better durability than older designs. The inventive device uses a passive capture design which allows assembly without additional fasteners or retaining devices while preventing disassembly during use. A combination three-point ball seat reduces the tee&#39;s mass and effect on the ball launch while acting as a handle to facilitate precise and easy height adjustment.

This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61/133,329 filed on Jun. 27, 2008, which is incorporated by reference in its entirety.

BACKGROUND

The most common type of practice golf tee in use today at commercial driving ranges when hitting from a mat is a hollow rubber-like tube of fixed height which extends from a circular flat base. The tube portion protrudes up through a hole in the hitting mat slightly larger than the diameter of the tube. It is held in place by a round flat base and the golf ball is placed on the round open end of the tube. When using this type tee, the golfer can only change the height of the teed ball by exchanging the tee for one with a longer or shorter tube section. This type of tee is still popular with range operators because it is inexpensive and simple. While many adjustable tees have been designed, most have not proven practical for multiple reasons, particularly complicated design, difficulty of use and poor performance, especially the inability to easily be adjusted over a wide range and retain the set height after multiple impacts. Many golfers would prefer an adjustable practice tee that allows them to simulate the multiple tee heights used when actually playing golf. Of the adjustable practice tees being marketed today, the threaded type is the only design that allows unlimited adjustment between the minimum and maximum limits of the design.

The threaded types utilize a base piece with a threaded cavity, into which a matching threaded ball holding stem or “tee” part is inserted in a nut-and-bolt fashion, allowing the center tee part to be twisted, threading it up and down in the base. One of the earliest threaded type adjustable tees is the Twistee-Tee marketed by Fiberbuilt Manufacturing Inc., a maker of golf hitting mats. It works best with their matching mat because it requires the rigid base piece to be fastened to the mat and also requires a hole or cavity under the tee to allow space for the four-inch long threaded center tee piece to be screwed or threaded down to the minimum position. While this design maximizes the adjustment range and the increased mass of the center “tee” part provides durability, it cannot be easily used with other mats and for some users the large tee does not simulate a real tee when struck.

The primary reason for the large diameter of the center part is to overcome the inherent decrease in strength caused by the external threads. Later threaded type designs use a similar but smaller and shorter threaded center stem or tee part together with a flexible matching threaded base which will fit a wide variety of existing mats. While this design has less adjustment range, it provides a more realistic hitting feel. The two piece design naturally limits the adjustment range to some fraction of the height of the base piece. Increasing the height of the base increases the adjustment range but makes the tee unacceptable for use with thin hitting mats because even in the full down position it is too tall for thinner mats which can commonly be less than one inch thick. Decreasing the height of the base piece allows for use in thin mat but limits the range of adjustment. The solution presented by the available tee makers is to offer two sizes; a taller model for thick mats and a shorter model for thin mats. The thick mat taller model has an acceptable range of adjustment but the shorter thin mat version is too tall and in the full down position is too short in the full up position for all the tee shots a golfer might wish to practice.

All the earlier threaded types have additional common design problems. The center “tee” or ball holding part has external threads which weaken its structure, causing it to be easily bent and have a tendency to not return to the original straight upright shape. It is a common mechanical practice to cut grooves into a cylindrical part in order to make it easier to bend and reduce its tendency to return to straight. The external threads also provide tear points when struck repeatedly by a club leading to early failure. The most widely marketed design sold as the GROOVE RT is now labeled “NEW & IMPROVED Stronger and More Durable”, in an effort to show that progress has been made against the inherent failure problems in the first marketed versions caused by the external thread design. The “improved” model also has two additional washer-like parts added to the original three in an effort to lessen disassembly during use indicate problems inherent in the design.

While several other adjustable practice tees have been invented, none are widely in use today because they fail to meet one or more of these requirements:

-   -   Universality. The tee must be usable with most if not all         popular hitting mats, both the large, thick, heavy type used at         commercial driving ranges and the smaller, thinner type designed         for light duty and residential use. It should install easily         without tools or modification of the mat.     -   Ease of Use. The adjustment should be so simple and intuitive         that little or no instruction is required by the user to adjust         the tee to the exact desired height repeatedly. The tee must         remain at the set height after multiple club impacts until the         user selects another height setting. Any design that allows the         user to push or pull the tee by hand to another position would         too easily allow the impact of the club to also push or pull the         tee to another position.     -   Durability. The tee must survive thousands of impacts from a         golf club and long exposure to weather. It should strongly         resist disassembly and have minimal openings that could allow         dirt and sand to enter and have no metal parts that can corrode         or rust. It should have smooth outer surfaces with no exposed         threads or grooves which would provide tear points and lessen         its tendency to return to the upright position after being bent         by impact or storage.     -   Simplicity of Design. To be inexpensive enough for wide         acceptance, the tee should consist of no more than three parts         and require simple minimal assembly. A design which eliminates         the need for fasteners and retaining mechanisms is far better         than one that requires them. The currently marketed “nut and         bolt” external threaded tee design uses 5 additional parts         (three rubber/plastic washer, one metal washer and a metal ring)         simply to hold the center tee part in place.     -   Large Range of Adjustment. The wide variety of both clubs used         and golfer's personal preferences of tee heights necessitates a         large adjustment range. This invention allows an adjustment         range of 1.5 inches from full down to full up in the three piece         model intended for thin mats, 250% greater than the two piece         thin mat models tee being marketed today.         The present invention is able to meet all these requirements by         incorporating specific material characteristics and shapes in a         new and unique design.

SUMMARY OF THE INVENTION

The invention provides an improvement to the existing practice golf tees in common use when hitting golf balls from mats at driving ranges, public and private indoor hitting areas, golf club fitting, testing and swing teaching stations, and when using electronic golf swing analyzers and golf simulation video games. It is not intended for use as a tee when actually playing golf on a golf course. It is a new design which overcomes the problems inherent in all of the currently available adjustable and non-adjustable practice tees.

BRIEF DESCRIPTION OF THE DRAWINGS

To further show the unique advantages of the invention, the following drawings have been included:

FIG. 1 is a perspective view of the thick mat version of the invention in the full up position.

FIG. 2 is a perspective view of the thick mat version of the invention in the full down position.

FIG. 3 is a perspective view of the unassembled thick mat version of the invention showing the threaded cavity of the base with hidden lines.

FIGS. 4A, 4B and 4C are detail and section views of the base piece of the thick mat version of the invention.

FIG. 5 is a detail perspective view of the stem part of the thick mat version of the invention.

FIGS. 6A and 6B are perspective section views of the assembled thick mat version of the invention.

FIG. 7 is a perspective view of the thin mat three part version of the invention in the full up position.

FIG. 8 is a perspective view of the unassembled thin mat version of the invention showing all three parts.

FIG. 9 is a perspective view of the thin mat three part version of the invention in the full down position.

FIG. 10 is a perspective view of the thin mat three part version of the invention in the full up position with the base and insert parts shown in section view.

FIG. 11 is a perspective view of the thin mat three part version of the invention with both stem and insert in intermediate positions.

DETAILED DESCRIPTION

FIG. 1 is a perspective view showing the commercial (thick mat) version of the assembled tee 10 in the full up position. FIG. 2 shows the same tee 10 in the full down position. The tee is easily adjusted to any height between full up and full down.

As shown in FIG. 3, the commercial (thick mat) version of the adjustable height golf practice tee of my invention consists of only two parts, the base piece 12 and the stem 14. The stem 14 is a single part comprising a main cylindrical shaft 15 with a three point ball seat 20 upper portion and a double male threaded cylindrical lower portion 18 having a larger diameter than the main shaft and a tapered bottom.

The configuration of a three point ball seat 20 atop a narrow smooth sided shaft 15 provides several advantages over the conventional round seat of most tees. By minimizing the surface contact between ball and tee to only three small areas, the tee has less chance of affecting the ball's launch trajectory. There is also less chance of the club making contact with the tee before impacting the ball and the decreased mass of the tee absorbs less of the club's energy. The three point shape also serves as a convenient handle by which the user turns the stem 14 to adjust it up (counterclockwise) or down (clockwise).

The base piece 12 has a circular flat flange portion 13 at the bottom and a tapered cylindrical upright portion 23 with an internal double female threaded cavity 17. There are openings at the bottom 19 and top 21 of the base and protrusions 22 on the underside of the flange to help prevent the base from turning when the stem 14 is turned for the purpose of adjustment.

FIGS. 4A, 4B, and 4C show details of the base piece 12. FIG. 4B shows a section view of the base 12 from the perspective indicated by the section line shown in FIG. 4A. FIG. 4C is a detail view of the upper portion of the section view of the base as identified in FIG. 4B. The threaded cavity 17 has two rounded female threads 16A, 16B which extend from the upper end 26 of the cavity 17 to the opening at the bottom 19. Additional to the primary function of facilitating the up and down travel of the stem 14, the female threads vary the thickness of the wall of the base (see FIG. 4B) giving it additional flexibility without weakening it at any single horizontal point as would occur if simple grooves or ribs were employed. All threads are internal to avoid exposure to the club impact and preserve the tendency of the part to return to the original shape after impact.

The stem support opening 24 is unthreaded and of the same diameter as the stem main shaft 15. A tapered top opening 21 provides access to the stem support opening 24 and a stop for the three point ball seat 20 when the stem is in the fully down position shown in FIG. 2.

The base 12 is made of urethane rubber with a hardness of 75 to 80 on the Shore hardness scale. The stem 14 is made of urethane rubber with a Shore 90A hardness. Both can be fabricated using a number of molding systems and procedures commonly known and used in the rubber and plastics industries. Other materials with very similar durability and elasticity might also be used with acceptable results.

The tee 10 is assembled by pressing the cylindrical lower portion 18 of the stem into the tapered top opening 21 and stem support opening 24, then twisting the stem 14 clockwise until the double male rounded threads shown in detail view of FIG. 5 on the tapered cylindrical portion 18 of the stem mate with the matching female rounded threads 16A, 16B of the threaded cavity 17 as shown in the section views FIG. 6A and FIG. 6B.

The unique combination of shapes, material hardness and elasticity incorporated into the design allow the stem 14 to be inserted into the base during assembly without damage to either piece. That unique combination also provides that, after assembly the stem is captured in the base and cannot be removed by hand or when repeatedly struck violently with a golf club. The flat upper surface 28 and mass of the double male threads incorporated into the lower portion of the stem (see FIG. 5 Detail View) prevent the stem from being extracted past the squared upper end 26 of the threaded cavity 17 in the base. The stem is easily adjusted to any position within the base such as the nearly full down position shown in FIG. 6B by simply turning it, using the three point ball seat 20 as a handle.

FIG. 7 shows the thin mat version of the adjustable height golf practice tee 30 of my invention in the full up position. FIG. 8 shows the three parts which make up the assembly. The stem 32 and base 36 are similar in both shape and function to the corresponding parts used in the thick mat version of the invention described above. This thin mat version utilizes an insert piece 34 to achieve a wide adjustment range while allowing the low minimum height shown in FIG. 9, required when being used with a thin hitting mat. The insert 34 has internal female threads (see FIG. 10) to mate with the external male threads of the stem. The insert threads up into the base from the bottom. The larger diameter lower threaded portion 35 of the insert prevents the insert from passing through the upper opening 37 of the base. The stem 32 is then pressed into the insert and twisted to mate the threads, locking the three parts together as a unit. As in the thick mat version details described above, the assembly utilizes double threads and a combination of design shapes that provide the flexibility, durability, ease of assembly and resistance to disassembly needed. All three parts of the thin mat version are made of urethane rubber with a hardness of 90 on the Shore A scale. Other materials with very similar durability and elasticity might also be used with acceptable results.

FIG. 10 shows the assembled tee with the base 36 and insert 34 shown in section view to illustrate the interaction of the male and female threaded portions of all three parts. All threads are internal to avoid exposure to the club impact and provide additional flexibility to the parts. The smooth outer surfaces afforded by utilizing only internal thread aid the stem and insert to return to their original shape after impact. The insert 34 and stem 32 can be raised and lowered independently as illustrated by FIG. 11, in which the insert is shown partially raised out of the base while the stem is partially raised out of the insert to achieve an intermediate position between full up and full down. 

1. An adjustable golf practice tee comprising: a) a base comprising a flat flange portion and a tapered cylindrical upright portion having a top and a bottom; wherein said tapered cylindrical upright portion comprises a double female threaded cavity and a bottom opening into which at least one concentric additional part may be inserted; wherein said cavity extends from said bottom opening to a lower end of an unthreaded concentric hole at the top of said upright portion of said base; and wherein said unthreaded concentric hole is of smaller diameter than said threaded cavity; and wherein said tapered cylindrical upright portion is wider near said flat flange portion; and b) a central ball support having a smooth cylindrical upper portion and a double male threaded lower portion, said double male threaded lower portion being situated to engage with said double female threaded cavity; wherein said double male threaded lower portion is of shorter length and greater diameter than said smooth cylindrical upper portion; wherein said double male threaded lower portion comprises a flat horizontal upper surface and a tapered lower end; and wherein said central ball support comprises a three pointed concave seat portion atop said smooth cylindrical upper portion, said seat portion extending from the top of said tapered cylindrical upright portion of said base; and wherein said base and said central ball support are made from a flexible durable material.
 2. The adjustable golf practice tee of claim 1, wherein at least one flexible durable concentric intermediate part is inserted into said base through said bottom opening, said at least one concentric intermediate part having a top and a bottom; a smooth cylindrical upper portion having a cylindrical top feature of larger diameter than said cylindrical upper portion; a double male threaded lower portion having shorter length and greater diameter than said smooth cylindrical upper portion and comprising a flat horizontal upper surface; and a double female threaded cavity open at the bottom, wherein said cavity extends from said bottom opening to a lower end of an unthreaded concentric hole at the top of said intermediate part, and wherein said unthreaded concentric hole is of smaller diameter than said threaded cavity; said cavity capable of accepting said central ball support and engaging said central ball support's double male threaded lower portion.
 3. The adjustable golf practice tee of claim 1, wherein the underside of said base comprises a plurality of gripper protrusions. 